Punching mechanism



Sept. 26, 1944. w, F. LEQNHART- PUNCHING MECHANISM Filed Ju'ne 17, 1945 I 2 Sheets-Sheet 1 awe/Mon W EL E ONHART z4 Patented Sept. 26, 1944 UNITED 2,359,226 PUNCHING MECIQTIANISM William F. Leonhart, Mount Lebanon, Pa., assignor to Owens-Illinois Can Company, a corporation of Delaware Application June 17, 1943, Serial, No. 491,097

13 Claims.

My invention relates to mechanism comprising shearing punches for shearing sheet material. The mechanism in the form herein illustrated, is particularly adapted for use in severing the corners from rectangular, fiat metal sheets which serve as body sheets in the process of making cans. In the manufacture of such cans, the rectangular sheets for forming the bodies are rolled to cylindrical form and the meeting edges welded together. The welding operation tends to produce a rough projection or bur at the end of the joint which interferes with satisfactory seaming of the body and end wall. The present invention provides means comprising notching punches for cutting off small corner pieces from the work sheet corresponding to the bur produced by the welding rollers, so that small notches are formed at the ends of the seam. This avoids such interference.

Conventional punching mechanism has been found inadequate and unreliable for the purpose of removing the very small corner sections with the required precision and accuracy. An object of the invention is to overcome this difliculty and to this end I have provided a novel mechanism for accurately positioning the work sheets and holding them in position for the punching operation. The invention further provides accurate and reliable means for holding and guiding the punches while punching the work sheets which are fed forward to the punching station in rapid succes- Other objects of the invention will appear hereinafter.

Referring to the accompanying drawings:

Fig. l is a plan view of the mechanism.

Fig. 2 is a sectional elevation at the line 22 on Fig. l.

Fig. 3 is a cross section at the line 33 on Fig. 1.

Fig. 4 is a fragmentary section at the line 4-4 on Fig. 1, showing particularly the locating device for positioning the work sheet preparatory to the punching operation.

Fig. 5 is a fragmentary sectional view at the line 5-5 on Fig. 2.

Fig. 6 is a section at the line 6--6 on Fig. 2.

Fig. '7 is a plan view of a sheet from which the corners have been severed.

Referring to the drawings, the operating mechanism is supported in part on a stationary framework including a platform ID on which ismounted a horizontal table ll providing a support for the Work sheets [2 during the punching operation. The workpieces l2 consist of rectangular metal sheets which are brought singly and in succession to the punching station. Conventional means may be employed for feeding the sheets, including a reciprocating feed bar or bars 8 (Figs. 1 and 2) and fingers 9. Each sheet as it advances into position for the punching operation, passes beneath holding devices comprising strips l3 extending lengthwise of the table. The strips l3 are held with a yielding pressure against the work sheets by means of coil springs l4 mounted on posts I5 attached to the strips. The springs are held under compression between strips l3 and brackets l6 which serve as means for positioning the holding strips. The posts l5 are screwthreaded to receive stop nuts I! which limit "the downward movement of the guide strips. The brackets I6 are mounted on guide rails l8which overlie the table I l in position to engage the side edges of the work sheets.

The punching mechanism includes a pair of rams 20 mounted to reciprocate vertically. The rams have bearings on guide posts 2| rising from the platform Ill. Means for reciprocating the rams includes an arm 22 connected to a horizon tal shaft 23 which is connected to depending arms 24 on the rams. The arm 22 may be connected to a crank or eccentric for reciprocating the rams in a conventional manner.

Notching punches 25 are arranged to shear the corners at the forward end of the sheet, and notching punches 26 sever the corners at the rear end of the sheet. Each punch is in the form of a vertical rod, square or rectangular in cross section and having a triangular strip cut away at one corner thereof along the lower portion of the rod, leaving a vertical face 21 (Figs. 5 and 6), the lower edge 28 of which forms the shearing edge of the punch. The punches are attached to the rams 20 by means of holders, each comprising clamping blocks 29 and 30. Clamping bolts 3| clamp said blocks to the punches and secure the holders to the rams. The holders are slidably mounted in guideways 32 extending lengthwise of the rams. The clamping bolts extend through slots 33 permitting adjustment of the holders.

The lower end portions of the punches are slidable up and down in guide blocks 34 (Figs. 5 and 6) which are clamped to the platform I!) by screw bolts 35. The latter extend through openings 36 in said blocks, the openings being elongated to permit adjustment of the punches lengthwise of the table. Stationary dies 34 beneath the guide blocks 34,- are formed with die openings 34* in register with the punches. of the die blocks are flush with the surface of the table II, and said blocks are clamped in place The upper surfaces l by the bolts 35. When the punches are in their raised position (Fig. the lower ends thereof are only a short distance above the work sheet [2, and in operation the punches have only a short vertical movement. This arrangement insures reliable and accurate operation in severing very small corner sections from the work sheets.

The work sheet I2 is accurately positioned and securely held in position during the punching operation by means of a pair of locating stop arms 31 arranged to engage the rear edge of the.

sheet, and locating rods 38 or punches arranged to engage the forward edge of the sheet and move it rearwardly into contact with the locating arms 3'! as the punches descend. The arms 31 are mounted by pivot pins 39 on holders 40 which are clamped torthe table by bolts 4| (Fig. 1) and are adjustable lengthwise of the table for adjustably varying the position of the stop The locating rods 38 are clamped to the punch holding blocks 30 by means of caps 42 and clamping bolts 43. The locating rods (as shown) are slightly inclined to the vertical and extend below the caps 42 in a, downward and forward direction. Each said rod is formed near its lower end with a contacting surface 39 (Fig. l) for engagement with the forward edge of the work sheet as the ram descends. The surface 39 is slightly inclined so that as it moves downward, it functions as a cam or locating surface and moves the work sheet rearwardly a slight distance so that at the moment the punches engage the work sheet, the latter is firmly held between the locating arms 31 and rods 38, thereby insuring accurate operation in severing th corners from the work sheet. I

In operation, the work sheets are moved forward over the table. II singly and in succession by the feeding mechanism, each sheet being brought to rest in a position in which the rear edge thereof is slightly in advance of the locating "arms 31 and held in such .position by the holding strips [3. With the sheet in this posi tion, the rams descend and the locating rods 38 operate, as above described, to position and hold the sheet while the punches operate.

Modifications may be resorted to within the spirit and scope of my invention.

I claim: V

l. The combination of a support, means for holding a work sheet on the support, a stop positioned adjacent one edge of the work sheet on said support, a punch positioned over said support and the work sheet thereon, means for lowering the punch, and a sheet positioning and holding device connected to move downward with the punch, said device having a surface inclined to its direction of movement and positioned to engage the opposite edge of the work sheet and force it against said stop as the punch to project behind the rear edge of a work sheet whenthe latteris moved onto the table, apunch positioned over the table, means for reciprocating the punch vertically and causingit to shear a corner from the work sheet, and a sheet locating device connected to. reciprocate with the punch, said locating device positioned to move downward in front of the sheet'and having an inclined sheet engaging surface.

3. Mechanism for severing corners from rectangular work sheets, including a table onto which the work sheets are fed horizontally, a locating stop mounted on the table in position to project behind the rear edge of a work sheet when the latter is moved onto the table, a punch positioned over the table, means for reciprocating the punch vertically and causing it to shear a corner from the work sheet, and a sheet locating device connected to reciprocate with the punch, said locating device positioned to move downward in front of the sheet and having a downwardly and forwardly inclined surface extending in front of the sheet in position to cam the sheet rearwardly as the punch moves downward and hold the sheet clamped against said stop during the shearing operation of the punch.

4. The combination of a table for supporting a work sheet, means for feeding the sheet forward onto the table, spring holding devices poforming a backstop for the sheet,guides positioned to engage the side edges .Oif the sheet as it moves onto the table and holding 'it against lateral movement, a punch mounted over the table and movable vertically downward in position to shear a corner from the sheet, and means for holding the sheet against said backstop during the shearing operation of the punch.

5. The combination of a table for supporting a work sheet, means for feeding the sheet forward onto the table, spring holding devices positioned over the table and including means for holding the work sheet with a yielding pressure on the table, a locating arm mounted over the table and arranged to drop behind the sheet as the latter is moved forward onto the table and forming a backstop for the sheet, guides positioned to engage the side edges of the sheet as it moves onto the table and holding it against lateral movement, a punch mounted over the table and movable vertically downward in position to shear a corner from the sheet, and means for moving the sheet rearwardly into engagement with said backstop as the punch descends, and holding it against said stop during the shearing operation of the punch.

6. The combination of a table for supporting a work sheet, a ram mounted for up and down movement, a vertical punch rod mounted on said ram, and a stationary guide positioned over the table and having an opening through which said rod is guided, the lower end of said guide being spaced. a. short distance above the table to permit the edge of the work sheet to pass therebeneath.

'7. Mechanism for severing corners from rectangular worksheets, including a table onto which the work sheets are fed horizontally, a locating stopmounted on the table in position to project behind the rear edge of a worksheet when the latter is moved onto the table, a punch positioned over the table, means for reciprocating, the punch vertically and causing it to shear a cornerfrom the worksheet, and a sheet locat ing and holding rod mounted to reciprocate with the'punch and having a forwardly and downwardly ,inclined' approximately vertical sheet-engagingsurface movable downward in front of the sheet as the punch descends and arranged to impart .a slight rearward movement to the sheet and clamp it in a fixed position against said stop and hold it in said position while the said punch shears a corner from said sheet.

8. The combination of a supporting table for a work sheet, a cutting punch comprising a vertical punching rod, means for reciprocating said rod vertically, a stationary die member mounted with its upper surface flush with said table and having a die opening to receive and guide the lower end of said rod, and a stationary guide block positioned above said die member and having a guide opening through which the said rod extends, said guide block having its lower end spaced a short distance above the level of the table.

9. The combination of a supporting table for a work sheet, a cutting punch comprising a vertical punching rod, and means for reciprocating said rod vertically, said punching rod being rectangular in cross section and having a lower corner portion cut away to provide a diagonal shearing edge, and means to hold the work sheet in position to have the corner thereof sheared off by the punch as the latter descends.

10. The combination of a supporting table for a work sheet, a cutting punch comprising a vertical punching rod, means for reciprocating said rod vertically, a stationary die member mounted with its upper surface flush with said table and having a die opening to receive and guide the lower end of said rod, a stationary guide block positioned above said die member and having a guide opening through which the said rod extends, said guide block having its lower end spaced a short distance above the level of the table, said punching rod being rectangular in cross section and having a lower corner portion cut away to provide a diagonal shearing edge, and means to hold the work sheet in position to have the corner thereof sheared off by the punch as the latter descends.

11. The combination of a horizontal table forming a support for work sheets, means for feeding a work sheet forward to a predetermined position on said table, guide bars positioned to engage the lateral edges of the work sheet and hold it against lateral movement on the table, spring-pressed holding bars positioned over the table beneath which the sheet is guided as it moves into said position, and by which it is held down on the table, a stop arm mounted over the table in position to drop behind a work sheet as the latter is brought to said position on the table, a punch positioned above the table and the Work sheet thereon, means for reciprocating the punch vertically, and means cooperating with the punch to move said sheet rearwardly and hold it against said stop arm.

12. The combination of a horizontal table forming a support for work sheets, means for feeding a work sheet forward to a predetermined position on said table, guide bars positioned to engage the lateral edges of the work sheet and hold it against lateral movement on the table, spring-pressed holding bars positioned over the table beneath which the sheet is guided as it moves into said position, and by which it is held down on the table, a stop arm mounted over the table in position to drop behind a work sheet as the latter is brought to said position on the table, a pair of rams positioned above and at opposite sides of the work sheet when the latter is in said position on the table, vertical punch rods connected to said rams and positioned over the corners of the work sheet while the latter is in said position on the table, and means for holding the work sheet against said stop arm.

13. The combination of a horizontal table forming a support for work sheets, means for feeding a work sheet forward to a predetermined position on said table, guide bars positioned to engage the lateral edges of the work sheet and hold it against lateral movement on the table, spring-pressed holding bars positioned over the table beneath which the sheet is guided as it moves into said position, and by which it is held down on the table, a stop arm mounted over the table in position to drop behind a work sheet as the latter is brought to said position on the table,

a pair of rams positioned above and at opposite sides of the work sheet when the latter is in said position on the table, vertical punch rods connected to said rams and positioned over the corners of the work sheet while the latter is in said position on the table, and means for holding the work sheet against said stop arm comprising locating bars connected to reciprocate with said rams and having sheet engaging surfaces arranged to be brought in front of the sheet as the rams descend and hold said sheet against said stop arm.

WILLIAM F. LEONHART. 

